Virtualization is the key. Having your application virtualized, users are able to use the application just by accessing it on the portal. The application is installed on the server where the portal is installed so users dont need the application installed in their systems. They just need to access the portal and click the icon of the application for them to use it. For us, we are using
Citrix[
^] for our desktop applications. There are tons of virtualization solutions in the market but perhaps you need to be familiar about the concept first.